Ink-jet recording apparatus

Abstract

An ink-jet recording apparatus is provided with an ink tank, a recording head, an ink passage extending from the ink tank to the recording head, and a sub-tank arranged on the ink passage. The apparatus has a first ink passage, a second ink passage, and an ultrasonic transducer. The first ink passage supplies ink from the ink tank to the sub-tank. The second ink passage has an ink outlet port, through which the ink is drawn from the sub-tank into the recording head. The ultrasonic transducer applies ultrasonic vibration to the ink contained in the sub-tank. The ink outlet port of the second ink passage is arranged near the ultrasonic transducer.

1. An ink-jet recording apparatus comprising an ink tank containing ink, a recording head, an ink passage extending from the ink tank to the recording head, and a sub-tank provided on the ink passage, wherein the ink-jet recording apparatus is configured to record images on a recording medium, and the apparatus further comprises:
 a first ink passage having an ink inlet port through which the ink is supplied from the ink tank to the sub-tank; 
 a second ink passage having an ink outlet port through which the ink is drawn from the sub-tank and supplied to the recording head; and 
 an ultrasonic transducer configured to generate an ultrasonic wave, thereby forming a standing-wave field in the ink contained in the sub-tank, wherein the standing-wave field has a sound-pressure antinode, and 
 wherein the ink outlet port of the second ink passage is arranged: (i) near the ultrasonic transducer, and (ii) at a position corresponding to the sound-pressure antinode of the standing-wave field. 
 
     
     
       2. The ink-jet recording apparatus according to  claim 1 , wherein the ultrasonic transducer is arranged on a bottom of the sub-tank, and the ink outlet port is arranged near said sound-pressure antinode that is formed before other sound-pressure antinodes, with respect to a direction in which the ultrasonic wave generated by the ultrasonic transducer propagates from the bottom of the sub-tank. 
     
     
       3. The ink-jet recording apparatus according to  claim 1 , wherein the ultrasonic transducer is arranged on a bottom of the sub-tank. 
     
     
       4. The ink-jet recording apparatus according to  claim 3 , wherein the ink outlet port of the second ink passage is provided near the bottom of the sub-tank. 
     
     
       5. The ink-jet recording apparatus according to  claim 2 , wherein the ink outlet port of the second ink passage opens upwards with respect to a direction of gravity. 
     
     
       6. The ink-jet recording apparatus according to  claim 4 , wherein the ink outlet port of the second ink passage opens upward with respect to a direction of gravity. 
     
     
       7. The ink-jet recording apparatus according to  claim 2 , wherein the ink outlet port of the second ink passage opens to a direction that is substantially at right angles to a direction of gravity. 
     
     
       8. The ink-jet recording apparatus according to  claim 4 , wherein the ink outlet port of the second ink passage opens to a direction that is a substantially at right angles to a direction of gravity. 
     
     
       9. The ink-jet recording apparatus according to  claim 1 , wherein the ultrasonic transducer is arranged substantially parallel to a shortest possible path along which the ink flows from the ink inlet port of the first ink passage to the ink outlet port of the second ink passage. 
     
     
       10. The ink-jet recording apparatus according to  claim 1 , further comprising at least one additional sub-tank, wherein the ultrasonic transducer is provided in common for said sub-tank and said at least one additional sub-tank. 
     
     
       11. The ink-jet recording apparatus according to  claim 10 , wherein the ultrasonic transducer is arranged on bottoms of said sub-tank and said at least one additional sub-tank. 
     
     
       12. The ink-jet recording apparatus according to  claim 11 , wherein the second ink passage includes a plurality of ink outlet ports that are provided near the bottoms of said sub-tank and said at least one additional sub-tank, respectively. 
     
     
       13. The ink-jet recording apparatus according to  claim 12 , wherein each of the plurality of the ink outlet ports of the second ink passage is arranged near a sound-pressure antinode of the standing-wave field. 
     
     
       14. The ink-jet recording apparatus according to  claim 13 , wherein each of the plurality of the ink outlet ports is arranged near a sound-pressure antinode which is formed first in a propagation direction of the ultrasonic wave emitted by the ultrasonic transducer and output from the respective bottoms of the sub-tanks. 
     
     
       15. The ink-jet recording apparatus according to  claim 10 , wherein the ultrasonic transducer is arranged between said sub-tank and said at least one additional sub-tank. 
     
     
       16. The ink-jet recording apparatus according to  claim 15 , wherein a plurality of ink outlet ports respectively corresponding to said sub-tank and said at least one additional sub-tank are arranged near the ultrasonic transducer. 
     
     
       17. The ink-jet recording apparatus according to  claim 16 , wherein each of the plurality of the ink outlet ports is arranged near a sound-pressure antinode which is formed first in a propagation direction of the ultrasonic wave emitted by the ultrasonic transducer. 
     
     
       18. The ink-jet recording apparatus according to  claim 1 , wherein the ultrasonic transducer is configured to be driven only when the apparatus prints data. 
     
     
       19. An ink-jet recording apparatus comprising an ink tank containing ink, a recording head, an ink passage extending from the ink tank to the recording head, and a sub-tank provided on the ink passage, wherein the ink-jet recording apparatus is configured to record images on a recording medium, and the apparatus further comprises:
 a first ink passage configured to supply the ink in the ink tank to the sub-tank; 
 a second ink passage configured to draw the ink in the sub-tank and supply the ink to the recording head; and 
 an ultrasonic transducer arranged on a bottom of the sub-tank and configured to generate an ultrasonic wave, thereby forming a standing-wave field in the ink contained in the sub-tank, 
 wherein an end portion of the second ink passage connected to the sub-tank is arranged at a position corresponding to an antinode of sound pressure of the standing-wave field. 
 
     
     
       20. The ink-jet recording apparatus according to  claim 19 , wherein the end portion of the second ink passage is arranged at the position corresponding to the antinode of sound pressure, which has been formed first in a propagation direction of the ultrasonic wave.